What is the main difference between extracting copper from low-grade ores and extracting metals by reduction with carbon?

The main difference is that extracting copper from low-grade ores often involves methods like bioleaching or phytomining, which utilize biological processes to extract metals. In contrast, reduction with carbon involves heating the metal ore with carbon to displace the metal from its oxide, typically used for high-grade ores.

A strong answer should directly address the approved learning objective to distinguish extracting copper from low-grade ores from extracting metals by reduction with carbon. This question belongs to Alternative methods of extracting metals within Using the Earth's resources and obtaining potable water, so the response should use that exact curriculum context rather than a generic statement. The answer is correct when it names the key idea, explains the link to low-grade ore, and keeps the wording specific to AQA GCSE revision.